<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>
  <script>
    var obj = {
      name: 'object'
    }
    var obj2 = {
      age: 10
    }
    var str = 'string'
    var num = 10;
    var und = undefined;
    var nan = NaN;
    var nul = null;
    var fal = false;
    var tru = true;

    console.log(obj && str);
    console.log(fal && obj);
    console.log(tru && obj);
    console.log(obj && obj2);
    console.log(nul && num);
    console.log(nan && num);
    console.log(und && num);
    console.log(num && bug);
    console.log('--------');
    console.log(fal && obj);
    console.log(fal && str);
    console.log(fal && num);
    console.log(fal && nul);
    console.log(fal && nan);
    console.log(fal && und);
  </script>
</body>
</html>